Sophie's World

by Jostein Gaarder

The single sense ideas are worked on by thinking, reasoning, believing, and doubting, thus giving rise to what he calls reflection. So he distinguished between “sensation” and “reflection.” The mind is not merely a passive receiver. It classifies and processes all sensations as they come streaming in. And this is just where one must be on guard.’ ‘On guard?’ ‘Locke emphasized that the only things we can perceive are simple sensations. When I eat an apple, for example, I do not sense the whole apple in one single sensation. In actual fact I receive a whole series of simple sensations – such as that something is green, smells fresh, and tastes juicy and sharp. Only after I have eaten an apple many times do I think: Now I am eating an “apple.” As Locke would say, we have formed a complex idea of an “apple.” When we were infants, tasting an apple for the first time, we had no such complex idea. But we saw something green, we tasted something fresh and juicy, yummy … It was a bit sour too. Little by little we bundle many similar sensations together and form concepts like “apple,” “pear,” “orange.” But in the final analysis, all the material for our knowledge of the world comes to us through sensations. Knowledge that cannot be traced back to a simple sensation is therefore false knowledge and must consequently be rejected.’ ‘At any rate we can be sure that what we see, hear, smell, and taste are the way we sense it.’ ‘Both yes and no. And that brings us to the second question L...